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Twenty-four steam-distilled samples of essential oils from inflorescences from Origanum vulgare ssp. hirtum (Link) Ietswaart growing wild in Calabria, southern Italy, were analyzed by gas chromatography and gas chromatography/mass spectrometry. A total of 56 compounds were identified. The main components of the essential oil were thymol and carvacrol, while their biogenetic precursors, p-cymene and γ-terpinene, were the most aboundant monoterpenes. The relative amounts of the two main constituents were comparable to the literature data on this species. Four chemotypes were identified in Calabria on the basis of the phenolic content, i.e., thymol, carvacrol, thymol/carvacrol, and carvacrol/thymol chemotypes. The first chemotype was the most frequent. A significant variability of composition possibly correlated with the individual genotypes was observed. Keywords: Oregano; Origanum vulgare ssp. hirtum; essential oil composition; GC/MS

The use of pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) to determine the molecular composition of lignocellulose is reviewed and the technique illustrated with applications on some novel systems. Constituents and structural arrangement of lignocellulosic polymers in plant cell wall are briefly described. The basic principles of pyrolysis and the main advantages and disadvantages of PY/GC/MS are discussed. PY/GC/MS analyses of (a) paper industry effluents, (b) agricultural by-products subjected to biological processes of delignification and (c) recycled paper are presented as examples of the amount of information that PY/GC/MS can provide on lignin classification and monitoring of delignification treatments as well as on the fingerprinting of lignocellulosic materials. The ion trap detector mass spectra of 56 pyrolysis products of lignocellulose, including compounds of phenolic, furanic and pyranic nature, are shown.

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Tannins from sorghum grains with high and low tannin content, from grape skins and seeds and from apple pomace were analysed by pyrolysis/gas chromatography/ion-trap detector mass spectrometry. Pyrolysis at 600 "C produced catechol as a characteristic fragment of condensed tannins, and other phenolic compounds related to the lignified tissues. Catechol was also the main fragment in the pyrogram of catechin, a monomeric constitutent of condensed tannins. Mass spectral data and relative quantifications of the pyrograms of several samples are provided. Quantitative data are discussed in terms of reproducibility and linearity of response and are compared with the results of a spectrophotometric assay for tannins.

The differential biodegradation of phenolic and nonphenolic (C-4-etherified) lignin units in wheat straw treated with the white rot fungi Pleurotus eryngii and Phanerochaete chrysosporium was investigated under solid-state fermentation conditions. Two analytical techniques applied to permethylated straw were used for this purpose, i.e., alkaline CuO degradation and analytical pyrolysis (both followed by gas chromatographymass spectrometry for product identification). Despite differences in the enzymatic machinery produced, both ligninolytic fungi caused a significant decrease in the relative amount of phenolic lignin units during the degradation process. Nevertheless, no differences in the biodegradation rates of phenolic and etherified cinnamic acids were observed. Changes in lignin composition and cinnamic acid content were also analyzed in the phenolic and nonphenolic lignin moieties. The results obtained are discussed in the context of the enzymatic mechanisms of lignin biodegradation.